Where is my History?

Updated to 160.0 a few days ago on my laptop. Went to view my History for reference today, only to find today's...and only today's...History, with NO previous dates. Hmmm and grrr. OK, am I logged in? Yes. Hmmm. OK, I share Sync with my mobile device; maybe they're "backed up" there. I use quotes because the unchecking of the History box in Sync could/will wipe them. So I looked at my mobile device, and the History check box was unchecked. Hmmm, possibly not good. History goes back at least 2 weeks, good. Last auto-sync 1-hour ago. I remember unchecking the box, for memory reasons, previously, some time ago. OK, let's check the box now, to Sync today's History from the laptop (still working on the mobile device...). The mobile device took a couple of minutes to Sync; the only device it was Syncing with, the laptop, only had 15 History pages in total! So what took so long? After that, I went to the laptop, and initiated Sync from that browser. At least a couple of minutes later, it was done, and the History was restored/recovered. QUESTION: Where was it restored from? Firefox account cloud backup storage via Sync? Local browser storage on my mobile device via Sync? Was this a glitch in vers. 160.0? release? Was there any instruction to re-Sync on the "What's New in Firefox 160.0" webpage? (Good thing I know a few things! But this is taking my time to diagnose!)